Effects of inbreeding on reproductive success, performance, litter size, and survival in captive red wolves (Canis rufus)

Abstract

Captive-breeding programs have been widely used in the conservation of imperiled species, but the effects of inbreeding, frequently expressed in traits related to fitness, are nearly unavoidable in small populations with few founders. Following its planned extirpation in the wild, the endangered red wolf (Canis rufus) was preserved in captivity with just 14 founders. In this study, we evaluated the captive red wolf population for relationships between inbreeding and reproductive performance and fitness. Over 30 years of managed breeding, the level of inbreeding in the captive population has increased, and litter size has declined. Inbreeding levels were lower in sire and dam wolves that reproduced than in those that did not reproduce. However, there was no difference in the inbreeding level of actual litters and predicted litters. Litter size was negatively affected by offspring and paternal levels of inbreeding, but the effect of inbreeding on offspring survival was restricted to a positive influence. There was no apparent relationship between inbreeding and method of rearing offspring. The observable effects of inbreeding in the captive red wolf population currently do not appear to be a limiting factor in the conservation of the red wolf population. Additional studies exploring the extent of the effects of inbreeding will be required as inbreeding levels increase in the captive population.

Effects of age and experience on reproductive performance of captive red wolves (Canis rufus)

“…A previous study investigated changes in age structure in the captive red wolf population and how those changes affected the population's reproductive potential (Lockyear et al 2009). However, the accuracy of the data set used in the previous study has been questioned (Rabon and Waddell 2010), and relatively few results of the effects of age on reproduction are similar between the two studies. For example, Lockyear et al (2009) reported that reproductive success was negatively correlated only with female age.…”

“…As part of a larger study of traits that affect reproduction (e.g., Rabon and Waddell 2010), I examined longitudinal reproductive events of captive red wolves to determine whether parental age, reproductive experience (i.e., prior sexual experience and prior reproductive success), and parental rearing type were factors in the production of offspring. I also examined longitudinal reproductive events to test the relationships between the parental age and reproductive experience of adult males and females and the following measures of reproductive fitness: litter size; litter rearing type; sex ratio of the litter; viability of offspring.…”

“…Under current conditions, gene diversity is expected to be maintained at or above 85% for at least 16 years (Waddell and Long 2013). However, inbreeding within the captive population has resulted in lower reproductive performance, smaller litter sizes, and reduced survivability of offspring (Rabon and Waddell 2010). Demographic projections to achieve the 5-year target population size (recently reduced to 200 individuals) require a 3% annual growth rate ( = 1.03), but current spatial limitations necessitate that the population maintain a 2% growth rate ( = 1.02) and approximately 26-35 births annually to offset the expected annual mortality rate (Waddell and Long 2013).…”

Genetic management of captive populations: the advantages of circular mating

“…Our model could also be applied to cases where even if captive populations increased in size, they remain initially small for several generations; see for instance, the ex-situ conservation of the Mauritius Kestrel (Falco punctatus) (Jones et al 1995), the Red Wolf (Canis rufus) (Rabon and Waddell 2010) or the Puerto Rican Crested Toad (Peltophryne lemur) (Beauclerc et al 2010).…”

Genome Banking for Vertebrates Wildlife Conservation

“…Inbreeding comes with a very high price with respect to the soundness of the reproductive system. This can be manifested in sperm quality (Roldan et al, 1998;Gomendio et al, 2000;Ruiz-Lopez et al, 2010) and in the outcome in term of litter size and survival (Rabon & Waddell, 2010). Once proper sample of sufficiently good quality is in hand, there are several options for its preservation.…”